Sealed secondary battery assembly

ABSTRACT

A sealed secondary battery assembly in which electricity-generating elements ( 1 ) are accommodated in battery cases ( 3 ) formed in rectangular tubular shape having a bottom, a plurality of cells ( 2   a  to  2   j ) constituted by sealing the apertures of battery cases ( 3 ) by covers ( 4 ) are arranged in series, and these are electrically connected by means of electrical connecting elements ( 9 ), wherein the battery cases ( 3 ) of the individual cells ( 2   a  to  2   j ) are constituted by a unitary battery case ( 51 ) and electrical connection elements ( 9 ) are arranged so as to pass through partition sections ( 53, 54 ) that define the space for the individual cells ( 2   a  to  2   j ), and coolant passages ( 55, 56 ) that communicate with the outside are formed in the partition sections ( 53, 54 ).

TECHNICAL FIELD

The present invention relates to a sealed secondary battery assemblyemployed for nickel-hydrogen secondary batteries or the likeconstituting the drive power source for an electric vehicle.

BACKGROUND ART

Sealed secondary battery assemblies of this type are previously knownand are disclosed in Laid-Open Japanese Patent Publication No.7-85847.This prior art example has a construction as shown in FIG. 16.Specifically, electricity generating elements are accommodated inbattery cases 36 formed in rectangular tubular shape having a bottom,the apertures of these battery cases 36 are sealed by covers 37 toconstitute cells 32, a plurality of which are arranged in series, thebattery cases 36 of these cells 32 being connected in tightly restrainedcondition by means of end plates 35 and restraining straps 34. Also,pillar-shaped positive electrode terminals 38 and negative electrodeterminals 39 of the cells 32 penetrate through covers 37 and projectabove them, these terminals 38 and 39 being electrically connected bymeans of an electrical connection bar 40.

However, with a construction as in the prior art example wherein batterycases 36 are tied together and held in restrained fashion by means ofend plates 35 and restraining straps 34, when the cells 32 expand as forexample during charging, a condition as shown in FIG. 17 is produced,with stress being concentrated at the portions indicated by P.

This stress concentration gives rise to creep deformation and as aresult the durability of battery cases 36 in regard to vibration orshock is severely impaired.

Also, in the case of a construction as in the prior art example in whichthe positive electrode and negative electrode terminals 38 and 39project above cover 37 and are electrically connected by an electricalconnection bar 40, the secondary battery is increased in height by theamount to which the positive electrode and negative electrode terminals38 and 39 project above cover 37; this is contrary to demands forincreased compactness. Also, there was the problem that sealing had tobe carried out individually between positive electrode and negativeelectrode terminals 38, 39 and cover 37 and if sealing was insufficientinternal liquid or gas could leak directly to the outside.

Also, with a construction as in the prior art example wherein theelectrical connection between the individual cells is effected on theoutside, the positive electrode and negative electrode terminals 38 and39 must be given a sealing function, electrical connection function, andfunction of effecting connection between themselves and theelectricity-generating elements within the batteries. The constructionof the positive electrode and negative electrode terminals 38 and 39therefore becomes complicated and costly, and, as a result, the totalcost of the sealed secondary battery assembly becomes high.

In the light of the above demands for compactness and demands forensuring sealing strength and lowering costs, the inventors of thepresent invention conceived, as a way of solving the problems of theprior art example, an internally connected construction whereinelectrical connection between the terminals is made within thebatteries. In this internally connected construction, as shown in FIG.19, electrical connection between two cells 32, 32 is made using anelectrical connecting rod 41 that passes through the connecting walls45, 45 of adjacent battery cases 36. Then, at the location Q whereelectrical connecting rod 41 passes through, the three items: electricalconnecting rod 41 and the two connecting walls 45, 45 are integrallycoupled by a resin welding technique.

However, if the internally connected construction shown in FIG. 18 isadopted, when cells 32 expand during charging etc., the condition shownin FIG. 17 is produced, with stress being concentrated in the portionsshown by Q in FIG. 18. Such stress concentration produces creepdeformation and this gives rise to the problem that the durability ofbattery cases 36 and electrical connecting rods 41 in regard tovibration and impact is severely impaired.

An object of the present invention is to solve the above problems and toprovide a sealed secondary battery assembly of excellent coolingconstruction.

DISCLOSURE OF THE INVENTION

In order to achieve the above objects, the present invention provides asealed secondary battery assembly in which electricity-generatingelements are accommodated in battery cases formed in rectangular tubularshape having a bottom, and a plurality of cells constituted by sealingthe apertures of these battery cases by covers are arranged in series,these cells being electrically connected by means of electricalconnection elements, characterized in that the battery cases of theindividual cells are constituted by a unitary battery case and theelectrical connection elements are arranged so as to pass throughpartition sections that define the space for the individual cells, andcoolant passages that communicate with the outside are formed in thepartition sections.

With the above construction, since the battery cases of the individualcells are constituted by a unitary battery case, even if the individualcells expand during charging etc., the stress that is generated underthese circumstances is not concentrated in a specific location (P ofFIG. 17 and Q of FIG. 18) but is dispersed to the entire partitionsection that defines the space of the individual cells. A sealedsecondary battery assembly of excellent durability in regard tovibration or impact can therefore be provided.

Also, with the above construction, the sealing structure becomes simple,since an internally connected structure i.e. a structure whereby theelectrical connection elements are arranged so as to pass through thepartition section is adopted. Also compactness of the secondary batterycan be achieved.

Furthermore, with the above construction, since coolant passages thatcommunicate with the outside are formed in the partition sections,effective cooling of the secondary battery can be achieved by forciblypassing cooling air for example to these coolant passages.

If a construction is adopted whereby the battery cases of the individualcells are separately manufactured and a unitary battery case isconstituted by joining up these battery cases, and irregularities areprovided on the connection face of each battery case in order to formcoolant passages, the following benefits are obtained. Since manufactureof the individual battery cases is easy and the width of the coolantpassages (gap in the direction of connection of the cells) can be madenarrower than with a unitary battery case consisting of a unitarymolding, to be described, the dimension of the sealed secondary batteryassembly in the cell connection direction can be made shorter i.e. itcan be made more compact. Specifically, owing to the difficulty of themolding technique, a unitary battery case consisting of a unitarymolding can only be formed with coolant passages of minimum width about5 mm; making this width any smaller is very difficult in terms of massproduction. However, if a construction is adopted in which the coolantpassages are formed on joining up the battery cases by providingirregularities for formation of coolant passages in the connecting facesof the individual battery cases, this width can be reduced down to about2 mm, so increased compactness of the sealed secondary battery assemblycan be achieved.

If a construction is adopted such that a projection is provided on theconnecting faces of each battery case and the coolant passages areformed by bringing these projections into abutment on connection,standardization of the individual battery cases is facilitated.

According to the above invention, if the battery cases are made of resinand these battery cases are joined up by welding or adhesion, a largemolding machine or the like for molding a unitary battery case isunnecessary, so manufacture of the sealed secondary battery assembly isfacilitated. The joining by welding or adhesion could be performed overthe entire surface between the connecting faces of the battery cases,excluding the spaces for formation of the coolant passages, but it couldalternatively be performed at the sides of the battery cases. The latteris suited in particular for joining by a welding operation.

On the other hand, as regards mass production characteristics, it isparticularly advantageous, where a construction is adopted whereby theunitary battery case consists of a unitary molding, for this unitarybattery case to be made of resin.

According to the above invention, if a construction is adopted wherebyend plates and restraining straps are arranged at the lateral peripheryof the unitary battery case, so that the unitary battery case isrestrained by these, the drawback that joining between battery cases isweak in regard to tensile strength can be overcome.

According to the above invention, if a construction is adopted wherebythe covers of the individual cells are constituted by a mutuallyintegrated unitary cover, in particular if the unitary cover is made aunitary resin molding, the apertures of the battery cases can all besealed at once by this unitary cover, thereby enabling efficiency of theoperation to be increased. Also, since the peripheries of the upperedges of the unitary battery case can be restrained by this unitarycover, in particular in the case of a unitary battery case of the typeconstituted by joining individual battery cases, increased durabilitycan be achieved.

According to the above invention, if the unitary cover is provided withapertures of the coolant passages, coolant can flow smoothly utilizingthese apertures, so a better cooling effect can be obtained.

The direction of formation of the coolant passages may be the verticaldirection, left/right direction, inclined vertical direction, or acombination of these. In particular, smooth flow of the coolant isobtained with the vertical direction.

In particular, if a construction is adopted wherein the apertures of thecoolant passages provided in the unitary cover are arranged alternatelyto left and right with respect to the center line in the direction ofconnection of the cells, and the electrical connection elements arearranged in symmetrical positions of the apertures and alternately toleft and right with respect to the center line, the flow of coolant inthe vertical direction is made smooth, thereby enabling a better coolingeffect to be achieved.

Further, in order to achieve the above object, the present inventionprovides a sealed secondary battery assembly whereinelectricity-generating elements are accommodated in battery cases formedin rectangular tubular shape having a bottom, and a plurality of cellsconstituted by sealing the apertures of these battery cases by coversare arranged in series, these cells being electrically connected bymeans of electrical connection elements, characterized in that theindividual cells are unified by being restrained by end plates andrestraining straps and the covers are constituted by a unitary coverconsisting of a unitary molding; the electrical connection elements arearranged so as to pass through partition sections that define the spacefor the individual cells, and coolant passages are formed in thepartition sections; and apertures communicating with these coolantpassages are provided in locations of the unitary cover corresponding tothe coolant passages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the whole of an embodiment of thepresent invention;

FIG. 2 is a perspective view showing the above embodiment with a unitarycover and unitary battery case in separated condition;

FIG. 3 is a plan view showing the unitary battery case;

FIG. 4 is a partially sectioned front view showing the unitary batterycase;

FIG. 5 is a plan view showing the unitary cover;

FIG. 6 is a cross-sectional view along the line E—E of FIG. 5 showingthe unitary cover;

FIG. 7 is a cross-sectional view showing the relationship between acover and a battery case;

FIG. 8 is a partially sectioned front view showing the battery case;

FIG. 9 is a bottom view showing the battery case;

FIG. 10 is a plan view showing various types of battery case;

FIG. 11 is a partially sectioned plan view showing the joined conditionbetween the battery cases;

FIG. 12 is a partially sectioned plan view showing an electricalconnection element and a support element thereof;

FIG. 13 is a perspective view showing the electrical connection elementand support element;

FIG. 14 is a front view showing the electrical connection element;

FIG. 15 is a cross-sectional view showing a modified example of theelectrical connection element and support element thereof;

FIG. 16 is a front view showing a prior art example;

FIG. 17 is a diagram showing problems of the prior art example; and

FIG. 18 is a diagram showing problems of the internally connectedconstruction.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention is described below with referenceto the drawings.

This embodiment relates to a nickel/hydrogen secondary battery assemblydeveloped as a drive power source for an electric vehicle. In thissecondary battery, as shown in FIG. 1 to FIG. 6, electricity-generatingelements 1 are accommodated in battery cases 3 made of resin formed inthe shape of rectangular tubes having a bottom; ten cells 2 a to 2 jconstituted by sealing the apertures of battery cases 3 by means ofcovers 4 made of resin are arranged in a row, and these are electricallyconnected in series.

The battery cases 3 of the cells 2 a to 2 j are mutually connected usingwelding means, thereby constituting a unitary battery case 51.

Covers 4 are constituted by a unitary cover 52 consisting of a unitaryresin molding whose internal space is divided into independent cells 2 ato 2 j by means of partition sections 53 (see FIG. 6) provided on thisunitary cover 52.

When battery cases 3 are joined up, the two adjacent joining walls 54 a,54 b constitute a partition section 54 that divides each cell 2 a to 2j. Cells 2 a to 2 j are electrically connected in series by arrangingelectrical connection elements 9 through partition sections 54 of thesebattery cases 3.

In partition sections 53 of covers 4 and partition sections 54 ofbattery cases 3, there are respectively formed coolant passages 55, 56that communicate with the outside. Cooling of cells 2 a to 2 j isperformed by forcibly passing cooling air through these coolant passages55, 56.

The battery cases 3 of cells 2 a to 2 j are integrally formed of resinsuch as PP/PPE alloy. On the outer surfaces (connecting faces) 57 ofjoining walls 54 a, 54 b constituting the side walls on the longest sideof these battery cases 3, there are arranged a plurality of air currentguides (projections) 15 for forming coolant passages 56. In the exampleshown in FIG. 8 and FIG. 9, in each case six air current guides 15 areprovided in projecting fashion extending in the form of strips in thevertical direction of respective outer surfaces 57 of the two joiningwalls 54 a, 54 b, including the air current guides 15 at both side ends.These air current guides 15 extend from the bottom face of battery case3 as far as a position about ¾ of the height of battery case 3; no aircurrent guides 15 are present in about the top ¼ of connecting face 57.In the regions where these air current guides 15 are not present, thereare provided a plurality of point-form projections 16 in the form ofshort cylindrical pillars to ensure proper spacing. The amount ofprojection of these point-form projections 16 from connecting face 57 isconstituted to be equal to that of air current guides 15.

In FIG. 8 and FIG. 9, 17 are position-locating recesses and 18 areposition-locating projections that fit into position-locating recesses17; these are provided on prescribed air current guides 15.

Also on the respective outer faces of left and right side walls 58 a, 58b constituting the side walls on the shortest sides of battery cases 3,there are provided in projecting fashion in the horizontal direction apair of upper and lower restraining ribs 104 that restrain movement inthe vertical direction of a restraining strap 14.

Furthermore, on the upper sides of the two joining walls 54 a, 54 b ofbattery cases 3, there are formed V-shaped recesses 11 a, 11 b. Onerecess 11 a is arranged offset in one direction in the left/rightdirection from the center of this upper side, while the other recess 11b is arranged offset in the other direction in the left/right directionfrom the center of this upper side.

In the example described above, recesses 11 a, 11 b were provided onrespectively both joining walls 54 a, 54 b of battery cases 3, butrecesses 11 a, 11 b are unnecessary, and in fact might be detrimental onthe side walls 54 c on the outside of battery cases 3 of cells 2 a, 2 jpositioned at both ends. Accordingly, as shown in FIG. 10, four types ofbattery case 3 were manufactured, taking into account the necessity forrecesses 11 a, 11 b and left/right symmetry. In FIG. 10, the batterycase indicated by A for use in cell 2 a is a battery case 3 that is notprovided with a recess S (indicated in FIG. 10 by hatching) on theoutside side wall 54 c. The battery case indicated by B is a batterycase 3 for cells 2 b, 2 d, 2 f, 2 h, as described with reference to FIG.8 and FIG. 9. The battery case indicated by C is an battery case 3 forcells 2 c, 2 e, 2 g, 2 i, having a recess S in a position symmetric withthe recess of B. The battery case indicated by D is a battery case forcell 2 j, wherein these are provided in positions symmetric with therecess of A and the outside side wall 54 c.

Ten battery cases 3 are mutually joined by welding to form a unitarybattery case 51. That is, as shown in FIG. 11 and FIG. 4, in a conditionwith air current guides 15 and point-form projections 16 of joiningwalls 54 a, 54 b of adjacent battery cases 3 abutting each other, andwith position-locating projections 18 located by fitting intoposition-locating recesses 17, battery cases 3 are joined up along theboundary lines N of two joining walls 54 a, 54 b (specifically, the lineof connection of air current guides 15 formed at the two side endparts), by heating the portions in the vicinity of this line fromoutside so that the resin is melted, then solidifying the resin. Also atthis point the recesses 11 a, 11 b of the two joining walls 54 a, 54 bthat are in joining relationship are in overlapping positions.

Coolant passages 56 that guide the air (coolant) in the upwardsdirection are formed by the two joining walls 54 a, 54 b, specifically,by air current guides 15, 15 provided on partition section 54, whenthese are in joining relationship. Also, in the approximately ¼ topportion of partition sections 54, by effecting contact of point-formprojections 16, 16 in an abutting condition, a space whereby air can beguided vertically and to left and right is formed between battery cases3. Consequently, air flow that is guided upwards by air current guides15 is guided towards covers 4 (upwards) and can be made to flow out atthe sides of battery cases 3 in the left/right direction.

In this embodiment, projections such as air current guides 15 areprovided on connecting faces 57 of each battery case 3 and coolantpassages 56 are formed by bringing fellow projections into contact whenjoining. The reason for this is that the amount of projection of aircurrent guides 15 or point-form projections 16 from connecting face 57can be made very small (for example of the order of 1 mm) and as aresult the width of coolant passage 56 in the cell connection directioncan be made small (for example of the order of 2 mm); this is thereforeadvantageous in achieving compactness of the sealed secondary batteryassembly.

For the joining of battery cases 3, apart from welding, adhesive couldbe employed. Also, adhesive joining or welding could be applied to allthe contacting portions of the two connection faces 57.

Electricity-generating elements 1 are accommodated in battery cases 3 asshown in FIG. 4. In electricity-generating element 1 constituted bystacking a plurality of positive electrode plates and negative electrodeplates with intervening separators and filling with electrolyte, apositive electrode terminal 5 at which are collected the leads from eachpositive electrode plate and a negative electrode terminal 6 at whichare collected the leads from each negative electrode plate are formed.Positive electrode terminal 5 is offset in one direction in theleft/right direction and negative electrode terminal 6 is arranged in aposition offset in the other direction in the left/right direction.

Positive electrode terminal post 7 is connected to positive electrodeterminal 5 of cell 2 a positioned at one end, while negative electrodeterminal post 8 is connected to negative electrode terminal 6 of cell 2j positioned at the other end. This positive electrode terminal post 7and negative electrode terminal post 8 constitute the positive electrodeand negative electrode terminals of the sealed secondary batteryassembly as a whole.

The pair of joining walls 54 a, 54 b that are in joining relationshipconstitute a partition section 54 that defines the space for each cellin unitary battery case 51. A metallic rod (electrical connectionelement) 9 made of nickel that passes through this partition section 54in the horizontal direction is fixed to a support element 19 integrallyformed of resin such as PP/PPE alloy. This support element 19 comprisesa holding tube 60 and a triangular flange 61 whose upper side ishorizontal. As shown in FIG. 12 and 13, metallic rod 9 is pressed intoand passes through holding tube 60 and is thereby held. Flange 61 fitsinto the recesses (support element mounting passage sections) 11 a, 11 bprovided in the upper side of connecting walls 54 a, 54 b. The internaldiameter of through-hole 66 of holding tube 60 is formed somewhatsmaller than the external diameter of metallic rod 9. Also the aperture80 at one end of holding tube 60 is formed so as to have an internaldiameter larger than that of the other portions. Flange 61 is providedwith two vanes 61 a, 61 b, an air flow space 68 being provided formedbetween the two vanes 61 a, 61 b on the left and right of flange 61.This air flow space 68 is beneficial in making the flow of cooling airsmooth. The two vanes 61 a, 61 b contact the respective recesses 11 a,11 b of joining walls 54 a, 54 b in one-to-one correspondence.

Metallic rod 9 is formed as a cylinder having a head 62 that is pressedinto holding tube 60. This metallic rod 9 is pressed into through-hole66 of support element 19. By applying ultrasonic vibration to metallicrod 9 during this pressing-in, the resin of support element 19 is meltedaround metallic rod 9 by frictional heating produced by this vibration.By this means, the pressing-in operation is made possible and takesplace in a smooth fashion; moreover, sealing characteristics areimproved by the solidification of the molten resin. An O-ring 21 isarranged in the aperture (holding groove) 80; during the pressing-in,this is compressed by head 62 of metallic rod 9. This compressed O-ring21 is in pressure contact with the circumference of metallic rod 9,thereby contributing to improvement in sealing. Also, soft stickysealant 63 is applied to the inner circumferential surface of aperture80 and metallic rod 9 and O-ring 21, thereby further improving sealing.

In this embodiment, the pressing-in operation was performed whileapplying ultrasonic vibration to metallic rod 9, but the pressing-inoperation could be performed while heating metallic rod 9, or whileapplying both heat and ultrasonic vibration to metallic rod 9.Furthermore, metallic rod 9 could simply be inserted into supportelement 19 simply by a pressing-in operation only.

Also, as shown in FIG. 15, it is possible to adopt an arrangement inwhich a plurality of grooves 64 are provided around the circumference ofmetallic rod 9 and a holding groove 65 is formed that holds O-ring 21,metallic rod 9 being pressed in into through-hole 66 of supportingelement 19, while applying ultrasonic vibration, heating or both ofthese. Soft sticky sealant 63 is applied to holding groove 65 andgrooves 64. By such an arrangement, a portion 67 of the resin of supportelement 19 is melted out into grooves 64 and by subsequentsolidification 5 movement in the axial direction of metallic rod 9 isrestrained, so that fixing of the metallic rod 9 into support element 19can be performed in a reliable fashion.

In this way, as shown in FIG. 3, FIG. 4 and FIG. 7, support element 19with the metallic rod (electrical connection element) 9 fixed thereto isfitted in by respectively bringing the pair of vanes 61 a, 61 b intocontact with the pair of recesses 11 a, 11 b provided in partitionsection 54 i.e. the pair of joining walls 54 a, 54 b, and is joined tojoining walls 54 a, 54 b by welding using a heat welder. If supportelement 19 and battery cases 3 are formed of the same type of resin, forexample PP/PPE alloy, the above welding operation can be performedsmoothly and reliably. Also, as shown in FIG. 7, the upper side ofsupport element 19 and the upper side of partition section 54 may beconstituted in a coplanar condition.

As shown in FIG. 2, FIG. 5, and FIG. 6, unitary cover 52 is integrallyformed using as raw material resin such as PP/PPE alloy, and is providedwith partition sections 53 for independently partitioning its internalspace into individual cells 2 a to 2 j. As shown in FIG. 6, thesepartition sections 53 comprise two partitions 53 a, 53 b and are formedwith an aperture 26 for releasing coolant air therein to the outside. Asshown in FIG. 5, these apertures 26 are arranged alternately on the leftand right of the center line in the direction of connection of thecells. Also the undersides of the two partitions 53 a, 53 b 30 contactin one-to-one correspondence the upper side of the two joining walls 54a, 54 b of partition section 54 of the battery case and the upper sidesof the two vanes 61 a, 61 b of support element 19.

In unitary cover 52, there are provided terminal post fixing holes 24for inserting and fixing positive electrode terminal posts 7 andnegative electrode terminal posts 8, a safety valve mounting hole 23 formounting a safety valve 28 (see FIG. 1) and a thermistor mountingsection 25 for mounting a thermistor for temperature measurement.

As shown in FIG. 7, a step 69 for fitting purposes is formed in expandedform at the outer periphery of the bottom edge of unitary cover 52.Unitary cover 52 is assembled on to unitary battery case 51 with thissuperimposed on a fitting step 70 provided at the upper edge of eachindividual battery case 3. Unitary cover 52 and unitary battery case 51are joined by welding or adhesion etc.

By joining up and unifying unitary cover 52 and unitary battery case 51,the two partition sections 53, 54 are brought into contact and the cells2 a to 2 j come to have respectively independent spaces. Also in the twopartition sections 53, 54, coolant passages 55, 56 that communicate witheach other and also communicate with the outside are formed.Specifically, when for example cooling air is forcibly made to flowupwards from the bottom face of unitary battery case 51, this aircurrent flows upwards guided by air current guides 15 until, at the topof battery case 3, at the location where point-form projections 16 areprovided, part of it flows out sideways while the rest flows out upwardsfrom apertures 26 provided in unitary cover 52. By means of such an airflow, the individual battery cases 3 constituting unitary battery case51 can be effectively cooled. It should be noted that, in order to makethe flow of this air smooth, as shown in FIG. 2, the apertures 26provided in unitary cover 52 are arranged alternately to left and rightwith respect to the center line in the direction of connection of thecells, and support elements 19 in which are fixed the electricalconnection elements (metallic rods) 9 are arranged alternately to leftand right with respect to the center line and in symmetric positions ofapertures 26.

Since unitary battery case 51 is joined by welding individuallymanufactured battery cases 3, there are some problems in relation to itstensile strength. In order to overcome this problem, end plates 13 arearranged on both outside ends of unitary battery case 51 and the ends ofa pair of left and right restraining straps 14 are coupled by rivets 22to these end plates 13 thereby binding unitary battery case 51 tightly.

Apart from the embodiment of the present invention illustrated above, itcould be constituted in various modes. For example, the unitary casecould be constituted by a unitary resin molding. Alternatively, aunitary cover could be constituted by joining up individuallymanufactured covers. Also, for the cover, it is not necessarilyessential to employ a unitary cover and a construction could be adoptedin which respectively independent covers are provided on each cell.Furthermore, the electrical connection elements could be fixed to thesupport elements by insert molding, or the electrical connectionelements could be directly fixed to the unitary battery case or unitarycover. Also, a sealed secondary battery assembly can be constructed byunifying the individual cells, without using adhesive or welding means,by restraining these by end plates and restraining straps andconstituting the covers by a unitary cover consisting of a unitarymolding and, as already described, arranging electrical connectionelements so as to pass through the partition sections that define theindividual cells and forming coolant passages in the partition sections,and, in addition, providing apertures that communicate with thesecoolant passages at locations of the unitary cover corresponding to theindividual coolant passages.

INDUSTRIAL APPLICABILITY

With the present invention, durability in regard to vibration or impact,an excellent cooling structure, compactness and a high degree of safetycan be achieved, so it is useful as a sealed secondary battery assembly.

What is claimed is:
 1. A sealed secondary battery assembly, comprising:electricity-generating elements; battery cell cases formed asrectangular tubes having a bottom, opposing partition walls and opposingside walls defining a cell case aperture, said electricity-generatingelements being disposed respectively in said battery cell cases; batterycell case covers sealing said cell case apertures to form a plurality ofsealed battery cells, said cell case covers being formed contiguous as aunitary cover; said battery cell cases being disposed serially adjacentone another and said partition walls having partition wall surfaces withcontacting portions contacting adjacent ones of said partition walls,said contacting portions being fixed together to form a unitary batterycase, said partition walls thereby forming partition sections of saidunitary battery case which partition said sealed battery cells from oneanother; electrical connection elements passing through said partitionsections, formed by the partition walls, to serially connect saidelectricity-generating elements without use of electrical connectionmembers extending through said battery cell case covers; and saidpartition walls defining coolant passages in said partition sections. 2.The sealed secondary battery assembly according to claim 1, wherein:said unitary battery case is formed by manufacturing said battery cellcases separately, and joining said battery cell cases at said contactingportions; and said partition wall surfaces having surface structurewhich defines said coolant passages.
 3. The sealed secondary batteryassembly of claim 2, wherein said surface structure includes projectionsprovided on said partition wall surfaces such that said coolant passagesare formed by abutment of said projections when said battery cell casesare joined.
 4. The sealed secondary battery assembly of claim 2, whereinsaid battery cell cases are made of resin and are joined by one ofwelding and adhesion.
 5. The sealed secondary battery assembly of claim4, wherein at least some of said battery cell cases are joined on bothof said partition wall surfaces.
 6. The sealed secondary batteryassembly of claim 1, wherein said unitary battery case is formed by aunitary molding.
 7. The sealed secondary battery assembly of claim 6,wherein said unitary battery case is made of resin.
 8. The sealedsecondary battery assembly of claim 1, further comprising: end platesdisposed on exposed ones of said partition wall surfaces at ends of saidunitary battery case; and restraining straps connecting said end platesand disposed about a lateral periphery of said unitary battery case torestrain said unitary battery case.
 9. The sealed secondary batteryassembly of claim 1, wherein said unitary cover is a resin unitarymolding.
 10. The sealed secondary battery assembly of claim 1, whereinsaid unitary cover defines cooling passage apertures acting as ports ofsaid coolant passages.
 11. The sealed secondary battery assembly ofclaim 10, wherein: said cooling passage apertures are provided in saidunitary cover alternating left and right with respect to a center lineextending in a direction of said serial disposal of said battery cellcases; and said electrical connection elements are arranged alternatingleft and right with respect to said center line.
 12. The sealedsecondary battery assembly of claim 1, wherein said coolant passageslead coolant in a vertical direction.
 13. A sealed secondary batteryassembly, comprising: electricity-generating elements; battery cellcases formed as rectangular tubes having a bottom, opposing partitionwalls and opposing side walls defining a cell case aperture, saidelectricity-generating elements being disposed respectively in saidbattery cell cases; battery cell case covers sealing said cell caseapertures to form a plurality of sealed battery cells; said battery cellcases being disposed serially adjacent one another and said partitionwalls having partition wall surfaces with contacting portions contactingadjacent ones of said partition walls thereby forming an assembledbattery case, said partition walls forming partition sections whichpartition said sealed battery cells from one another; end platesdisposed on exposed ones of said partition wall surfaces at ends of saidassembled battery case; restraining straps connecting said end platesand disposed about a lateral periphery of said assembled battery case topull together said battery cell cases to form said assembled batterycase; said battery cell case covers being serially disposed and formedas a unitary cover which is a unitary molding; electrical connectionelements passing through said partition sections, formed by thepartition walls, to serially connect said electricity-generatingelements without use of electrical connection members extending throughsaid battery cell case covers; said portion walls defining coolantpassages in said partition sections; and said battery cell case coversdefining apertures communicating with said coolant passages and disposedat locations said unitary cover corresponding to said coolant passages.